Method for controlling operating speed and torque of electric motor

ABSTRACT

Systems and methods for controlling the operating speed and the torque of an electric motor using an operational model are described. An operational model for the electric motor, including a plot of engine performance parameters, is used for reference, and a most efficient output path, which may pass through an optimal operation region in the operational model, is selected. The most efficient output path may be determined, for example, according to locations of a current output state and a to-be-reached target state in the operational model, enabling the operating state of the motor to reach the target state from the current operating state. By selecting a more efficient output path, the operating efficiency of the motor may be optimized, the life of a battery improved and/or the operating mileage of the vehicle may be increased, without significantly reducing the driving experience.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 14/826,217, filed Aug. 14, 2015, which claimspriority to U.S. Provisional Patent Application No. 62/133,991, filed onMar. 16, 2015, and U.S. Provisional Patent Application No. 62/150,848,filed on Apr. 22, 2015, the disclosures of which are hereby incorporatedby reference in their entireties for all purposes.

BACKGROUND

The present disclosure relates to control technologies for use with anelectric motor, such as in an electric vehicle, and, in some examples,relates to methods for controlling the operating speed and the torque ofan electric motor in an operational model for an electric vehicle.

New environmental-friendly and energy-saving electric vehicles involvenew fields of technological development, many of which are in need offurther improvement in order to continue to expand the market prospectsof such vehicles. One area of particular concern involves the limitedenergy storage of a battery of an electric vehicle. Therefore, reducingenergy loss (to increase vehicle mileage) is particularly important, andenergy-saving technology for the electric motor is a key factor in thisdevelopment.

Currently, electric vehicles may be configured to adopt an ECO mode (ora limp-in mode) to reduce power output and power consumption to prolongthe vehicle mileage. However, such methods prolong the mileage at thecost of, for example, reducing the power output to decelerate, andreducing the power consumption of electrical components of the vehicle,and can unfavorably limit, or fail to satisfy, driving requirement ofthe vehicle.

SUMMARY

Exemplary embodiments of the present disclosure may address at leastsome of the above-noted problems. For example, according to firstaspects of the disclosure, a method for controlling the operating speedand torque of an electric motor in an operational model is provided. Inembodiments, the operational model may include a plurality of operationpositions and an optimal operation region of the electric motor. Inembodiments, each operation position may correspond to a speedparameter, a torque parameter and an operating efficiency parameter ofthe electric motor. Embodiments may include one or more of storing theoperational model in a storage device; detecting a current speedparameter and a current torque parameter corresponding to a currentoperation position of the electric motor in the operational model;inputting a target speed parameter and a target torque parametercorresponding to a target operation position of the electric motor inthe operational model; determining whether the current operationposition is located in the optimal operation region according to thecurrent speed parameter and the current torque parameter of the electricmotor; if the current operation position is not located in the optimaloperation region, adjusting the current speed parameter and/or thecurrent torque parameter along a first path to move the currentoperation position to an intermediate operation position whichcorresponds to an intermediate speed parameter and an intermediatetorque parameter and is located in the optimal operation region; andadjusting the intermediate speed parameter and the intermediate torqueparameter to move the intermediate operation position to the targetoperation position along a second path.

According to further aspects of the disclosure, other methods forcontrolling the operating speed and torque of an electric motor in anoperational model may include one or more of storing the operationalmodel in a storing device; detecting a current speed parameter and acurrent torque parameter corresponding to the current operation positionof the electric motor in the operational model; inputting a target speedparameter and a target torque parameter corresponding to a targetoperation position of the electric motor in the operational model;determining whether the current operation position is located in theoptimal operation region according to the current speed parameter andthe current torque parameter of the electric motor; if the currentoperation position is not located in the optimal operation region,determining whether to select an intermediate operation position in theoptimal operation region or directly move the current operation positionto the target operation position without selecting an intermediateoperation position in the optimal operation region; if there is a needto select the intermediate operation position in the optimal operationregion, adjusting at least one of the current speed parameter and thecurrent torque parameter along a first path to move the currentoperation position to the intermediate operation position whichcorresponds to an intermediate speed parameter and an intermediatetorque parameter and is located in the optimal operation region; andadjusting the intermediate speed parameter and the intermediate torqueparameter to move the intermediate operation position to the targetoperation position along a second path.

According to further aspects of the disclosure, an operational model maybe adopted and implemented by systems and methods described herein,providing an efficient output path passing through an optimal operationregion in the operational model, when needed, according to the currentoutput state and the to-be-reached target state of a motor, enabling theoperating state of the motor to efficiently reach the target state fromthe current operating state. In some examples, such control systems mayprovide benefits, such as optimizing the operating efficiency of themotor, improving the life of the drive battery and/or increasing theoperating mileage, without significantly reducing the drivingexperience. Vehicles including engine controllers configured accordingto the disclosed methods are also included.

Additional features, advantages, and embodiments of the disclosure maybe set forth or apparent from consideration of the following detaileddescription, drawings, and claims. Moreover, it is to be understood thatboth the foregoing summary of the invention and the following detaileddescription are exemplary and intended to provide further explanationwithout limiting the scope of the invention claimed. The detaileddescription and the specific examples, however, indicate only preferredembodiments of the invention. Various changes and modifications withinthe spirit and scope of the invention will become apparent to thoseskilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the detailed description serve to explain the principlesof the invention. No attempt is made to show structural details of theinvention in more detail than may be necessary for a fundamentalunderstanding of the invention and various ways in which it may bepracticed. In the drawings:

FIG. 1 is a module diagram of an exemplary electric vehicle motorefficiency control system according to aspects of the presentdisclosure.

FIG. 2 is a motor efficiency control flow diagram according to aspectsof the present disclosure.

FIG. 3A is a first example of a motor operating state in an operationalmodel according to aspects of the present disclosure.

FIG. 3B is a second example of a motor operating state in an operationalmodel according to aspects of the present disclosure.

FIG. 3C is a third example of a motor operating state in an operationalmodel according to aspects of the present disclosure.

FIG. 3D is a fourth example of a motor operating state in an operationalmodel according to aspects of the present disclosure.

FIG. 4 is a correction flow diagram for an operational model accordingto aspects of the present disclosure.

FIG. 5A is an operational model correction diagram according to anembodiment of the present disclosure.

FIG. 5B is an operational model correction diagram according to anotherembodiment of the present disclosure.

DETAILED DESCRIPTION

Various example embodiments of the present disclosure will be describedbelow with reference to the drawings constituting a part of thedescription. It should be understood that, although terms representingdirections are used in the present disclosure, such as “front”, “rear”,“upper”, “lower”, “left”, “right”, and the like, for describing variousexemplary structural parts and elements of the present disclosure, theseterms are used herein only for the purpose of convenience of explanationand are determined based on the exemplary orientations shown in thedrawings. Since the embodiments disclosed by the present disclosure canbe arranged according to different directions, these terms representingdirections are merely used for illustration and should not be regardedas limiting. Wherever possible, the same or similar reference marks usedin the present disclosure refer to the same components.

Unless defined otherwise, all technical terms used herein have the samemeanings as commonly understood by one of ordinary skill in the art towhich the invention pertains. The embodiments of the invention and thevarious features and advantageous details thereof are explained morefully with reference to the non-limiting embodiments and examples thatare described and/or illustrated in the accompanying drawings anddetailed in the following description. It should be noted that thefeatures illustrated in the drawings are not necessarily drawn to scale,and features of one embodiment may be employed with other embodiments asthe skilled artisan would recognize, even if not explicitly statedherein. Descriptions of well-known components and processing techniquesmay be omitted so as to not unnecessarily obscure the embodiments of theinvention. The examples used herein are intended merely to facilitate anunderstanding of ways in which the invention may be practiced and tofurther enable those of skill in the art to practice the embodiments ofthe invention. Accordingly, the examples and embodiments herein shouldnot be construed as limiting the scope of the invention, which isdefined solely by the appended claims and applicable law. Moreover, itis noted that like reference numerals reference similar parts throughoutthe several views of the drawings.

FIG. 1 is a module diagram of an exemplary electric vehicle motorefficiency control system according to aspects of the presentdisclosure. As shown in FIG. 1, a control system for controlling anelectric vehicle may include a battery pack 110, a motor driving circuit103, a motor 104, a sensor 105, a center console 106 (including a CPU109), a driving input system 107, a memory 108 and the like. The batterypack 110 provides the motor 104 with operating power; the motor drivingcircuit 103 may be connected between the motor 104 and the battery pack110 to transmit the power of the battery pack 110 to the motor 104, andthe working state of the motor 104 may be controlled by controlling thevoltage/current transmitted to the motor 104. The sensor 105 may be usedfor sensing the current operating parameters (e.g. the speed and thetorque) of the motor 104 and sending the operating parameters to thecenter console 106. According to these parameters, the center console106 can judge the current operating state of the motor 104 and send acontrol signal to the motor driving circuit 103 to change thevoltage/current input to the motor 104, thus changing the operatingstate of the motor. The center console 106 may be further connected withthe driving input system 107 and the memory 108. The driving inputsystem 107 may be configured to input the target operating state of themotor 104 to the center console 106, the memory 108 may be used to storea motor operational model, and the center console 106 may be configuredto read data from and write data into the motor operational model.

The operational model (See, e.g., FIG. 3A to FIG. 3D) may be a motoroperating efficiency table obtained by pre-simulating various operatingstates of the motor 104, and may include a set of multiple operationpositions (operating states) of the motor. Each operation position maycorrespond to a plurality of operating parameters of the motor. Forexample, the first-dimensional parameter may represent the output torqueof the motor (represented by a vertical coordinate), and thesecond-dimensional parameter may represent the speed of the motor(represented by a transverse coordinate).

In the operational model shown in FIG. 3A to FIG. 3D, each operationposition further corresponds to a motor operating efficiency parameter.A motor optimal operation region may be defined in the motor operatingefficiency table. For example, the motor optimal operation regionconsists of the region surrounded by the (innermost) boundary 1 in FIG.3A to FIG. 3D and the boundary 1. The motor optimal operation regionencompasses part of the operation positions, and the operatingefficiency values of the motor are relatively high in these operationpositions. The present disclosure enables the motor to pass through themotor optimal operation region and then reach the target state so as toconsume minimal or less energy when needed. Exemplary control steps arefurther described with reference to FIG. 2.

FIG. 2 is a motor efficiency control flow diagram of the presentdisclosure. Each operation depicted therein may represent a sequence ofoperations that can be implemented in hardware or computer instructionsimplemented in hardware. In the context of computer instructions, theoperations represent computer-executable instructions stored on one ormore computer-readable storage media that, when executed by one or morephysical processors, perform the recited operations. Generally,computer-executable instructions include routines, programs, objects,components, and the like that perform particular functions or implementparticular data types. The order in which the operations are describedis not intended to be construed as a limitation, and any number of thedescribed operations can be combined in any order and/or in parallel toimplement the processes. Additionally, any specific reference to one ormore operations being capable of being performed in a different order isnot to be understood as suggesting that other operations may not beperformed in another order.

The flow may begin with 201, in which a motor operating efficiency table(operational model) may be pre-stored, e.g. in the memory 108.

The flow may continue with 202, in which a sensor (e.g. 105) senses thecurrent operating parameters of the motor (e.g. 104), including speedand output torque, and sends the current operating parameters to acontroller/processor, such as the center console 106. Thecontroller/processor may calculate the position in the motor operatingefficiency table that corresponds to the current operating parameters(e.g. using the processor (CPU) 109), so as to obtain the currentoperation position of the motor on the motor operating efficiency table.

The flow may continue with 203, in which a driving input system (e.g.107) inputs target operating parameters (speed and torque), and thecontroller/processor calculates the position in the motor operatingefficiency table that corresponds to the target operating parameters, soas to obtain the target operation position of the motor.

The flow may continue with 204, in which the controller/processor maydetermine whether the current operation position of the motor 104 is inthe motor optimal operation region. If not, the flow may continue with205; or if yes, the flow may continue with 211.

If the flow proceeds to 205, the controller/processor may seek anintermediate operation position in the motor optimal operation region,and determine a first path from the current operation position to theintermediate operation position, a second path from the intermediateoperation position to the target operation position and/or a third pathfrom the current operation position to the target operation position. Insome examples, the intermediate operation position may be a position onthe boundary of the motor optimal operation region which is closest tothe current operation position of the motor, the first path may be theshortest path from the current operation position to the intermediateoperation position, the second path may be the shortest path from theintermediate operation position to the target operation position, andthe third path may be the shortest path from the current operationposition to the target operation position.

The flow may proceed from 205 to 206, in which the controller/processormay determine whether there is a need to optimize the operating state ofthe motor; if yes, the flow may continue with 207; otherwise, the flowmay proceed to 211.

In 207, the controller/processor may send an instruction to a motordriving circuit (e.g. 103) to adjust the input voltage and/or current tothe motor, so as to enable the operating state of the motor (e.g. 104)to reach the intermediate operation position from the current operationposition along the first path determined in 205.

The flow may proceed from 207 to 208, in which the controller/processormay send an instruction to the motor driving circuit to adjust the inputvoltage/current of the motor, so as to enable the operating state of themotor to reach the target operating position from the intermediateoperation position along the second path determined in 205.

Returning to 211, which may follow either of 204 or 206 as describedabove, the controller/processor may send an instruction to the motordriving circuit to adjust the input voltage/current of the motor, so asto enable the operating state of the motor to reach the target operatingposition from the current operating position along the third pathdetermined in 205.

After the operating state of the motor is enabled to reach the targetoperating position in 211 or 208, the flow may continue with 209, inwhich (according to the actual operating efficiency of the motor) thecontroller/processor may write data into memory to correct the storedmotor operating efficiency table (see also FIG. 4).

The flow may continue with 210, in which the controller/processor maydetermine whether the motor stops operating; if yes, the controloperation may be ended; otherwise, the flow may return to 202.

Further details regarding an exemplary method of determining theintermediate operating position, the first path, the second path and thethird path, and how to judge whether there is a need to optimize theoperating state of the motor to improve the operating efficiency of themotor, will be described below in conjunction with several examples ofthe motor operating state in the operational model of the presentdisclosure as shown in FIG. 3A to FIG. 3D.

FIG. 3A is a first example of the motor operating state in theoperational model of the present disclosure, wherein, the currentoperation position of the motor is not within the optimal operationregion.

In the motor operational model (motor operating efficiency table) asshown in FIG. 3A, regions circled by boundaries 1, 2, 3 and 4 representdifferent operating efficiency values, wherein the region in theboundary 1 (including the boundary 1) is defined as the optimaloperation region, namely a high-efficiency operating region, theefficiency of which is denoted by ξ_(α). The efficiency of the regionbetween the boundary 1 and boundary 2 (including the boundary 2) isdenoted by ξ_(β), the efficiency of the region between the boundary 2and boundary 3 (including the boundary 3) is denoted by ξ_(χ), theefficiency of the region between the boundary 3 and boundary 4(including the boundary 4) is denoted by ξ_(σ), and the efficiency ofthe region beyond the boundary 4 is denoted by ξ_(τ). The efficiency hasthe highest value in the high-efficiency region, and the efficiencyvalues are progressively decreased outwards, namelyξ_(α)>ξ_(β)>ε_(χ)>ξ_(σ)>ξ_(τ). In FIG. 3A, point A represents thecurrent operation position of the motor, point B represents theintermediate operation position, and point C represents the targetoperation position.

As described in step 205 of FIG. 2, the intermediate operation positionB is the position on the boundary 1 of the motor optimal operationregion which is closest to the current operation position A.Specifically, the intermediate operation position B may be calculated bythe following method:

-   1) Supposing there are N points O₁, O₂ . . . O_(n) on the boundary 1    of the high-efficiency operating region;-   2) Respectively calculating the linear distance between each of the    N points O₁, O₂ . . . O_(n) and the point A by the following method:-   denoting the coordinates of the N points as O₁(W₁, T₁), O₂ (W₂, T₂)    . . . O_(n) (W_(n), T_(n)) respectively, the coordinate of the point    A is denoted as (W_(A), T_(A)), wherein W represents the value of    speed and T represents the value of torque; denoting the linear    distance between each point and the point A as D_(i) (i=1, 2, 3 . .    . or n), wherein D_(i) is calculated in the following way:

$\begin{matrix}{{D_{1} = \sqrt{\left( {W_{1} - W_{A}} \right)^{2} + \left( {T_{1} - T_{A}} \right)^{2}}};} \\{{D_{2} = \sqrt{\left( {W_{2} - W_{A}} \right)^{2} + \left( {T_{2} - T_{A}} \right)^{2}}};} \\\ldots \\{{D_{n} = \sqrt{\left( {W_{n} - W_{A}} \right)^{2} + \left( {T_{n} - T_{A}} \right)^{2}}};}\end{matrix}$

-   3, Selecting the point O_(i) which has the shortest linear distance    (namely D_(i) is the smallest one) from the point A as the point B.

After the point B serving as the intermediate operation position isdetermined, the first, second and third paths are also determined. Thefirst path is the linear path from the current operation position A tothe intermediate operation position B, the second path is the linearpath from the intermediate operation position B to the target operationposition C, and the third path is the linear path directly from thecurrent operation position A to the target operation position C.

After the intermediate operation position, the first path, the secondpath and the third path are determined, whether there is a need tooptimize the operating state of the motor as described in step 206 canbe judged. According to an exemplary method of the present disclosure,if there is a need to optimize the operating state of the motor, themotor firstly reaches the intermediate operation position B from thecurrent operation position A along the first path, and then reaches thetarget operation position C from the intermediate operation position Balong the second path (namely the motor operates along the path ABC). Ifthere is no need to optimize the operating state of the motor, the motordirectly reaches the target operation position C from the currentoperation position A along the third path (namely the motor operatesalong the path AC). Whether there is a need to optimize the operatingstate of the motor is determined by comparing the energy consumed whenthe motor operates along the path ABC with that along the path AC; ifthe energy consumed along the path ABC is relatively low, then it isdetermined that there is a need to optimize the operating state of themotor; and if the energy consumed along the path AC is relatively low,then it is determined that there is no need to optimize the operatingstate of the motor.

A specific judging method is as follows:

-   1) Defining an operation goal: moving the operating state of the    motor from the point A to the point C within an operation time t and    reducing the consumption of input electric energy, namely reducing    the energy consumption of the motor;-   2) Defining the efficiency of the motor as ξ: ξ is the value    obtained by dividing the output mechanical energy of the motor by    the input electric energy of the motor;-   3) Defining a sampling time as t_(s): 1 second per point (the value    can be defined otherwise), so each of the path ABC and the path AC    together with their end points (points A and C) has t sampling    points;-   wherein the mechanical energy output of the motor on each sampling    point is E_(m) (kJ)=W (rpm)*T (Nm)*t_(s) (sec)/9550, W (rpm)    represents the speed of the motor, T (Nm) represents the output    torque, and 9550 is a conversion constant;-   the electric energy input of the motor on each sampling point is:    E _(θ) =E _(m)(kJ)/ξ;-   4) Summating the electric energy on each sampling point on each path    to obtain the electric energy consumed when the motor operates along    the path, and comparing the total electric energy consumption    E_(ABC) of the path ABC mode with the total electric energy    consumption E_(AC) of the path AC mode:    wherein the electric energy E_(ABC) consumed along the path ABC is:

$E_{ABC} = {\frac{1}{9550}{\sum\limits_{i = 1}^{t}\;\frac{W_{i}*T_{i}*1}{\xi_{i}}}}$the electric energy E_(AC) consumed along the path AC is:

$E_{AC} = {\frac{1}{9550}{\sum\limits_{j = 1}^{t}\;\frac{W_{j}*T_{j}*1}{\xi_{j}}}}$

If E_(ABC)<E_(AC), the electric energy E_(ABC) consumed along the pathABC is lower and therefore more economic, so it is determined that themotor operates along the path ABC to optimize the operating state of themotor; otherwise, there is no need to optimize the operating state ofthe motor, and the motor operates along the path AC.

The above judging method will be exemplarily described below inconjunction with the first example of the motor operating state in theoperational model as shown in FIG. 3A.

Specifically, as shown in FIG. 3A, the points A, B and C aretriangularly arranged, the distance between A and C is the longest, andAC is the longest side of the triangle. For simplifying the calculation,it is supposed that the operation time is 3 seconds; at the point A, thespeed is 1000 rpm, the torque is 100 Nm and the efficiency is 0.6; atthe point B, the speed is 1500 rpm, the torque is 120 Nm and theefficiency is 0.9; and at the point C, the speed is 2000 rpm, the torqueis 100 Nm and the efficiency is 0.6. For simplicity, the three points A,B and C are taken as sampling points on the path ABC; the point A, themidpoint of AC line and the point C are taken as sampling points on thepath AC. Then, the electric energy E_(ABC) consumed when the motoroperates along the path ABC is:

$E_{ABC} = {{\frac{1}{9550}\left( {\frac{100*1000}{0.6} + \frac{120*1500}{0.9} + \frac{100*2000}{0.6}} \right)} = {73.3\mspace{14mu}{kJ}}}$the electric energy E_(AC) consumed when the motor operates along thepath AC is:

$E_{AC} = {{\frac{1}{9550}\left( {\frac{100*1000}{0.6} + \frac{100*1500}{0.6} + \frac{100*2000}{0.6}} \right)} = {78.5\mspace{14mu}{kJ}}}$Thus, E_(ABC)<E_(AC), the electric energy consumed along the path ABC islower and therefore more economic, so it is judged accordingly thatthere is a need to optimize the operating state of the motor, and themotor is controlled to move from the current operation position to thetarget operation position along the path ABC.

FIG. 3B is a second example of the motor operating state in anoperational model of the present disclosure, wherein the currentoperation position of the motor is not in the optimal operation region.The above judging method will be exemplarily described in conjunctionwith the example shown in FIG. 3B.

As shown in FIG. 3B, the points A, B and C are triangularly arranged, ACand AB are equal in distance, and the distance between B and C is thelongest. For simplifying the calculation, it is supposed that theoperation time is 3 seconds; at the point A, the speed is 1000 rpm, thetorque is 100 Nm and the efficiency is 0.6; at the point B, the speed is1000 rpm, the torque is 120 Nm and the efficiency is 0.9; and at thepoint C, the speed is 2000 rpm, the torque is 100 Nm and the efficiencyis 0.6. For simplicity, the three points A, B and C are taken assampling points along the path ABC; the point A, the midpoint of AC lineand the point C are taken as sampling points along the path AC. Then,the electric energy E_(ABC) consumed when the motor operates along thepath ABC is:

$E_{ABC} = {{\frac{1}{9550}\left( {\frac{100*1000}{0.6} + \frac{120*1000}{0.9} + \frac{100*2000}{0.6}} \right)} = {66.3\mspace{14mu}{kJ}}}$the electric energy E_(AC) consumed when the motor operates along thepath AC is:

$E_{AC} = {{\frac{1}{9550}\left( {\frac{100*1000}{0.6} + \frac{100*1500}{0.6} + \frac{100*2000}{0.6}} \right)} = {78.5\mspace{14mu}{kJ}}}$

Thus, E_(ABC)<E_(AC), the electric energy consumed along the path ABC islower and therefore more economic, so it is judged accordingly that hereis a need to optimize the operating state of the motor, and the motor iscontrolled to move from the current operation position to the targetoperation position along the path ABC.

FIG. 3C is a third example of the motor operating state in anoperational model of the present disclosure, wherein the currentoperation position of the motor is not in the optimal operation region.The above judging method will be exemplarily described in conjunctionwith the example shown in FIG. 3C.

As shown in FIG. 3C, the points A, B and C are triangularly arranged,the distance between A and C is the shortest, and the distance between Band C is the longest. For simplifying the calculation, it is supposedthat the operation time is 3 seconds; at the point A, the speed is 1500rpm, the torque is 100 Nm and the efficiency is 0.6; at the point B, thespeed is 1000 rpm, the torque is 300 Nm and the efficiency is 0.9; andat the point C, the speed is 2000 rpm, the torque is 100 Nm and theefficiency is 0.6. For simplicity, the three points A, B and C are takenas sampling points along the path ABC; the point A, the midpoint of ACline and the point C are taken as sampling points along the path AC.Then, the electric energy E_(ABC) consumed when the motor operates alongthe path ABC is:

$E_{ABC} = {{\frac{1}{9550}\left( {\frac{100*1500}{0.6} + \frac{300*1000}{0.9} + \frac{100*2000}{0.6}} \right)} = {96.0\mspace{14mu}{kJ}}}$the electric energy E_(AC) consumed when the motor operates along thepath AC is:

$E_{AC} = {{\frac{1}{9550}\left( {\frac{100*1500}{0.6} + \frac{100*1750}{0.6} + \frac{100*2000}{0.6}} \right)} = {91.6\mspace{14mu}{kJ}}}$

Thus, E_(ABC)>E_(AC), the electric energy consumed along the path AC islower and therefore more economic, so it is judged accordingly thatthere is no need to optimize the operating state of the motor, and themotor is controlled to move from the current operation position to thetarget operation position along the path AC.

In sum, the selection of the path is related with the positions of thethree points A, B and C on the motor operating efficiency table andtheir respective efficiencies. In principle, the path ABC mode isrelatively applicable when the torque difference of the two points AB issmall and the speed difference of the two points AC is large.

FIG. 3D is a fourth example of the motor operating state in theoperational model of the present disclosure, wherein the currentoperation position of the motor is in the optimal operation region.According to the control flow diagram shown in FIG. 2, when the currentoperation position of the motor is in the optimal operation region, itis directly judged that there is no need to optimize the operating stateof the motor as carried out in FIGS. 3A-3C, and the motor is controlledto move from the current operation position to the target operationposition along the path AC. That is to say, when the current operationposition of the motor is in the optimal operation region, if anintermediate operation position B is also determined for the motor, theenergy consumed by the motor along the path ABC will be greater thanthat along the path AC. It may be verified by the following calculation.

For simplicity likewise, it is supposed that the operation time is 3seconds, at the point A, the speed is 1500 rpm, the torque is 400 Nm andthe efficiency is 0.9; at the point B, the speed is 1400 rpm, the torqueis 350 Nm and the efficiency is 0.9; and at the point C, the speed is2000 rpm, the torque is 50 Nm and the efficiency is 0.6. For simplicity,the three points A, B and C are taken as sampling points along the pathABC; the point A, the midpoint of AC line and the point C are taken assampling points along the path AC. Then, the electric energy E_(ABC)consumed when the motor operates along the path ABC is:

$E_{ABC} = {{\frac{1}{9550}\left( {\frac{400*1500}{0.9} + \frac{350*1400}{0.9} + \frac{50*2000}{0.6}} \right)} = {144.3\mspace{14mu}{kJ}}}$the electric energy E_(AC) consumed when the motor operates along thepath AC is:

$E_{AC} = {{\frac{1}{9550}\left( {\frac{400*1500}{0.9} + \frac{225*1750}{0.8} + \frac{50*2000}{0.6}} \right)} = {138.8\mspace{14mu}{kJ}}}$Thus, E_(ABC)>E_(AC).

FIG. 4 is a correction flow diagram of an exemplary operational model ofthe present disclosure. Each operation depicted therein may represent asequence of operations that can be implemented in hardware or computerinstructions implemented in hardware. In the context of computerinstructions, the operations represent computer-executable instructionsstored on one or more computer-readable storage media that, whenexecuted by one or more physical processors, perform the recitedoperations. Generally, computer-executable instructions includeroutines, programs, objects, components, and the like that performparticular functions or implement particular data types. The order inwhich the operations are described is not intended to be construed as alimitation, and any number of the described operations can be combinedin any order and/or in parallel to implement the processes.Additionally, any specific reference to one or more operations beingcapable of being performed in a different order is not to be understoodas suggesting that other operations may not be performed in anotherorder.

In the aforementioned operating mode control method, simulated test datavalues before the motor and/or vehicle is assembled may be used, and, inactual use of the motor, errors may exist between the actual operatingefficiency of the motor and the simulated data. Therefore, it may beadvantageous to correct the stored operational model, e.g. in real time.For example, the operational model may be corrected at some interval, orafter each time the motor operates to a target position. The datawritten by the controller/processor into the memory for correcting thestored motor operating efficiency table in step 209 as shown in FIG. 2may be obtained by a correction flow, such as shown in FIG. 4.

In 401, a controller/processor may calculate the input electric energyof the motor according to the input voltage and current of the motor atthe target running position C. The input voltage and current of themotor at the target running position C can be detected, for example,from the driving circuit by a sensor.

The flow may continue with 402, in which the controller/processor maycalculate the output mechanical energy from the motor, e.g. according tothe torque and the speed detected by sensor(s), of the motor at thetarget operation position C.

The flow may continue with 403, in which the controller/processor maycalculate the motor actual operating efficiency at the target operationposition C.

The flow may continue with 404, in which the controller/processor maycalculate a correction coefficient according to the operation efficiencycorresponding to the target operation position in the operational model(namely the theoretical operating efficiency) and the actual operatingefficiency of the motor at the target operation position calculated in403.

The flow may continue with 405, in which the controller/processor maydetermine at least one position C′ to be corrected close to the targetoperation position C.

The flow may continue with 406, in which the controller/processor maycalculate the distance H between the target operation position C and theposition C′ to be corrected.

The flow may continue with 407, in which the controller/processor maycalculate a correction quantity is calculated according to thecorrection coefficient calculated in step 404 and the distance Hcalculated in step 406.

The flow may continue with 403, in which the position of the position C′that is to be corrected in the operational model is corrected accordingto the correction quantity, and the data is stored to memory.

An exemplary method of correcting the position of the position C′ thatis to be corrected in the operational model according to the correctionquantity in step 407 is as follows:

-   1) supposing that the target position C is located between the    boundary 3 and the boundary 4, wherein the boundary 3 is closer to    the high-efficiency region, and the boundary 4 is farther from the    high-efficiency region;-   2) supposing that the theoretical efficiency of the target position    C between the boundary 3 and the boundary 4 is ξ_(τ) and the    actually measured efficiency is ξ_(χ), then calculating the    correction coefficient α=(ξ_(χ)−ξ_(τ))/10%;-   3) if the correction coefficient is a positive value, selecting a    point C′ closest to the point C on the boundary 3; if the correction    coefficient is a negative value, selecting a point C′ closest to the    point C on the boundary 4; wherein the distance between the two    points C and C′ is H;-   4) correcting the point C′ into a position which is αH far from the    point C on the linear path of CC′.

Thus, whenever the motor operates to a target position, the operationalmodel may be corrected once. In this way, during each correction, theposition of a point on an efficiency boundary may be changed, theposition of the efficiency boundaries in the motor operational modelwith respect to the transverse coordinate and the vertical coordinatemay be changed after multiple times of correction, and such a change canenable the motor operational model to be closer to the actual operatingcondition of the motor. That is to say, even if the actual operatingefficiencies of the motor are changed along with the use of the motor,the motor operational model still can reflect the actual operatingconditions of the motor by adopting the correction method of the presentdisclosure.

The above-mentioned correction method will be described below inconjunction with two embodiments as shown in FIG. 5A and FIG. 5B.

FIG. 5A is an operational model correction diagram according to anembodiment of the present disclosure. As shown in FIG. 5A, it issupposed that the efficiency within the boundary 1 is 90%, theefficiency between the boundaries 1 and 2 is 80%, the efficiency betweenthe boundaries 2 and 3 is 70%, and the efficiency between the boundaries3 and 4 is 60%;

-   1) supposing that the point C is a target position, it is located    between the boundaries 3 and 4 and has a theoretical efficiency of    60% and the actually measured efficiency when the motor reaches the    point C is 65%, then calculating the correction coefficient    α=(actually measured efficiency−theoretical efficiency)/10%=0.5;-   2) because the actually measured efficiency is greater than the    theoretical efficiency, a point C′ on the boundary 3 closest to the    point C is selected, and the distance of CC′ is H;-   3) because the calculated correction coefficient is 0.5, the point    C′ is corrected into the midpoint of line CC′, namely a position    which is between C and C′ and is 0.5H far from the point C.

FIG. 5B is an operational model correction diagram according to anotherembodiment of the present disclosure. As shown in FIG. 5B, it issupposed that the efficiency within the boundary 1 is 90%, theefficiency between the boundaries 1 and 2 is 80%, the efficiency betweenthe boundaries 2 and 3 is 70%, and the efficiency between the boundaries3 and 4 is 60%;

-   1) supposing that the point C is a target position, it is located    between the boundaries 3 and 4 and has a theoretical efficiency of    60%, and the actually measured efficiency when the motor reaches the    point C is 55%;-   2) because the actually measured efficiency is smaller than the    theoretical efficiency, a point C′ on the boundary 4 closest to the    point C is selected, and the CC′ distance is H;-   3) the correction coefficient=(actually measured    efficiency−theoretical efficiency)/10%=0.5, so the point C′ is    corrected into the midpoint on line CC′, namely a position which is    between C and C′ and is 0.5H far from the point C.

Although the present disclosure has been described with reference to thespecific embodiments shown in the drawings, it should be understood thatthe lightweight fastening methods provided by the present disclosure canhave a variety of variations without departing from the spirit, scopeand background of the present disclosure. The description given above ismerely illustrative and is not meant to be an exhaustive list of allpossible embodiments, applications or modifications of the invention.Those of ordinary skill in the art should be still aware that,parameters in the embodiments disclosed by the present disclosure can bechanged in different manners, and these changes shall fall within thespirit and scope of the present disclosure and the claims. Thus, variousmodifications and variations of the described methods and systems of theinvention will be apparent to those skilled in the art without departingfrom the scope and spirit of the invention.

What is claimed is:
 1. A method of operating an electric vehicle bycontrolling the operating speed and torque of an electric motor of theelectric vehicle in accordance with an operational model, wherein theoperational model comprises a plurality of operation positions of theelectric motor and an optimal operation region of the electric motor,each operation position indicating at least a value for a speedparameter, a torque parameter and an operating efficiency parameter ofthe electric motor, the optimal operation region includes one or more ofthe operation positions, the method comprising: storing, by a processor,the operational model in a storage device; detecting, by a sensor, thecurrent speed parameter and the current torque parameter correspondingto the current operation position of the electric motor in theoperational model; receiving, by a driving input system, a target speedparameter and a target torque parameter corresponding to a targetoperation position of the electric motor in the operational model; inresponse to the target speed parameter and target torque parameter beingreceived, adjusting, by the processor, the current operation position tothe target operation position, wherein the adjusting comprises:determining whether the current operation position is located in theoptimal operation region according to the current speed parameter andthe current torque parameter of the electric motor; and in response tothe current operation position being determined not located in theoptimal operation region: generating a first instruction to adjust atleast one of the current speed parameter and the current torqueparameter along a first path to move the current operation position toan intermediate operation position corresponding to an intermediatespeed parameter and an intermediate torque parameter and located in theoptimal operation region; and generating a second instruction to adjustthe intermediate speed parameter and the intermediate torque parameterto move the intermediate operation position to the target operationposition along a second path; and executing, by the processor, the firstand second instructions to adjust the current operation position to thetarget operation position.
 2. The method of claim 1, wherein adjustingthe current operation position to the target operation position furthercomprising: selecting an optimal intermediate operation position in theoptimal operation region as the intermediate operation position.
 3. Themethod of claim 2, wherein: the optimal intermediate operation positionis selected as a position having a shortest linear distance from theoptimal operation region to the current operation position.
 4. Themethod of claim 1, wherein the first instruction and second instructioninclude: changing the driving voltage and the driving current applied tothe electric motor.
 5. The method of claim 1, wherein adjusting thecurrent operation position to the target operation position furthercomprises: amending an efficiency parameter on a selected position inthe operational model according to a calculated efficiency parameter onthe target operation position.
 6. The method of claim 5, wherein:amending the efficiency parameter on a selected position in theoperational model according to the calculated efficiency parameter onthe target operation position comprises: detecting the input voltage andcurrent of the motor at the target operation position: calculating theactual operating efficiency of the motor at the target operationposition according to the torque and the speed of the motor at thetarget operation position and the detected input voltage and current atthe target operation position; calculating a correction coefficientaccording to the operating efficiency corresponding to the targetoperation position in the operational model and the calculated actualoperation efficiency of the motor at the target operation position;selecting at least one position to be corrected close to the targetoperation position; calculating the distance between the targetoperation position and the position to be corrected; calculating acorrection quantity according to the calculated correction coefficientcalculated and the calculated distance; correcting the position of theposition to be corrected in the operational model according to thecorrection quantity.
 7. A method of operating an electric vehicle by forcontrolling the operating speed and the torque of an electric motor ofthe electric vehicle in accordance with an operational model, whereinthe operational model comprises a plurality of operation positions ofthe electric motor and an optimal operation region of the electricmotor, each operation position indicates at least a value for a speedparameter, a torque parameter and an operating efficiency parameter ofthe electric motor, the optimal operation region includes one or more ofthe operation positions, the method comprising: storing, by a processor,the operational model in a storing device; detecting, by a sensor, thecurrent speed parameter and the current torque parameter correspondingto the current operation position of the electric motor in theoperational model; receiving, by a driving input system, a target speedparameter and a target torque parameter corresponding to a targetoperation position of the electric motor in the operational model; inresponse to the target speed parameter and target torque parameter beingreceived, adjusting, by the processor, the current operation position tothe target operation position, wherein the adjusting comprises:determining whether the current operation position is located in theoptimal operation region according to the current speed parameter andthe current torque parameter of the electric motor; in response todetermining the current operation position is not located in the optimaloperation region, determining whether to select an intermediateoperation position in the optimal operation region or directly move thecurrent operation position to the target operation position withoutselecting an intermediate operation position in the optimal operationregion; and in response to determining to select the intermediateoperation position in the optimal operation region: generating a firstinstruction to adjust at least one of the current speed parameter andthe current torque parameter along a first path to move the currentoperation position to the intermediate operation position whichcorresponds to an intermediate speed parameter and an intermediatetorque parameter and is located in the optimal operation region; andgenerating a second instruction to adjust the intermediate speedparameter and the intermediate torque parameter to move the intermediateoperation position to the target operation position along a second path;and executing, by the processor, the first and second instructions toadjust the current operation position to the target operation position.8. An electric vehicle motor controller, comprising: a processor; and astorage device including an operational model stored thereon, theoperational model including a plurality of operation positions and anoptimal operation region of an electric motor, each operation positioncorresponding to a speed parameter, a torque parameter and an operatingefficiency parameter of the electric motor; and, wherein the processoris configured to: detect, by a sensor, a current speed parameter and acurrent torque parameter of the electric motor; determine the currentspeed parameter and the current torque parameter corresponding to thecurrent operation position of the electric motor in the operationalmodel; receive, by a driving input system, a target speed parameter anda target torque parameter corresponding to a target operation positionof the electric motor in the operational model; in response to thetarget speed parameter and target torque parameter being received,adjust the current operation position to the target operation position,wherein the adjusting comprises: determining whether the currentoperation position is located in the optimal operation region accordingto the current speed parameter and the current torque parameter of theelectric motor; and in response to the current operation position beingdetermined not located in the optimal operation region: generating afirst instruction to adjust at least one of the current speed parameterand the current torque parameter along a first path to move the currentoperation position to an intermediate operation position correspondingto an intermediate speed parameter and an intermediate torque parameterand located in the optimal operation region; and generating a secondinstruction to adjust the intermediate speed parameter and theintermediate torque parameter to move the intermediate operationposition to the target operation position along a second path; andexecuting, the first and second instructions to adjust the currentoperation position to the target operation position.
 9. The controllerof claim 8, wherein adjusting the current operation position to thetarget operation position comprises selecting an optimal intermediateoperation position in the optimal operation region as a vertex of thesecond path.
 10. The controller of claim 9, wherein: the optimalintermediate operation position is selected as a position having ashortest linear distance from the optimal operation region to thecurrent operation position.
 11. The controller of claim 8, wherein thefirst instruction and second instruction include controlling theelectric motor according to the first or second path by changing atleast one of the driving voltage and the driving current applied to theelectric motor such that the current operation position at any timeduring the transition to the target operation position is on theselected transition path in the operational model.
 12. The controller ofclaim 8, wherein adjusting the current operation position to the targetoperation position comprises: amend an efficiency parameter on aselected position in the operational model according to a calculatedefficiency parameter on the target operation position.
 13. Thecontroller of claim 12, wherein: amending the efficiency parameter on aselected position in the operational model according to the calculatedefficiency parameter on the target operation position comprises:detecting the input voltage and current of the motor at the targetoperation position; calculating the actual operating efficiency of themotor at the target operation position according to the torque and thespeed of the motor at the target operation position and the detectedinput voltage and current at the target operation position: calculatinga correction coefficient according to the operating efficiencycorresponding to the target operation position in the operational modeland the calculated actual operation efficiency of the motor at thetarget operation position; selecting at least one position to becorrected close to the target operation position; calculating thedistance between the target operation position and the position to becorrected; calculating a correction quantity according to the calculatedcorrection coefficient calculated and the calculated distance:correcting the position of the position to be corrected in theoperational model according to the correction quantity.
 14. An electricvehicle comprising: an electric drive motor; a battery configured topower the electric drive motor; and an electric vehicle motor controllerincluding a central processing unit (CPU) and a memory with anoperational model stored therein, the operational model including aplurality of operation positions of the electric motor and an optimaloperation region of the electric motor, each operation positionindicating at least a value for a speed parameter, a torque parameterand an operating efficiency parameter of the electric motor, the optimaloperation region includes one or more of the operation positions, andthe CPU is configured to: detect, by a sensor, the current speedparameter and the current torque parameter of the electric drive motor;determine a current operation position of the electric drive motor inthe operational model based on the current speed parameter and thecurrent torque parameter: receive, by a driving input system, a targetspeed parameter and a target torque parameter corresponding to a targetoperation position of the electric motor in the operational model; inresponse to the target speed parameter and target torque parameter beingreceived, adjust the current operation position to the target operationposition, wherein the adjusting comprises: determining whether thecurrent operation position is located in the optimal operation region;in response to the current operation position being determined notlocated in the optimal operation region, determining whether to selectan intermediate operation position in the optimal operation region ordirectly move the current operation position to the target operationposition without selecting an intermediate operation position in theoptimal operation region; and send control signals configured totransition the electric drive motor from the current operation positionto the target operation position on the operational model.
 15. Thevehicle of claim 14, wherein the processor is further configured to: inresponse to determining to select the intermediate operation position inthe optimal operation region: adjust at least one of the current speedparameter and the current torque parameter along a first path to movethe current operation position to the intermediate operation positionwhich corresponds to an intermediate speed parameter and an intermediatetorque parameter and is located in the optimal operation region; andadjust the intermediate speed parameter and the intermediate torqueparameter to move the intermediate operation position to the targetoperation position along a second path.
 16. The vehicle of claim 15,wherein the processor is further configured to: select an optimalintermediate operation position in the optimal operation region as theintermediate operation position, wherein the optimal intermediateoperation position is selected as a position having a shortest lineardistance from the optimal operation region to the current operationposition.
 17. The vehicle of claim 14, wherein the control signals areconfigured to transition the electric drive motor from the currentoperation position to the target operation position on the operationalmodel by changing at least one of the driving voltage and the drivingcurrent applied to the electric motor such that the current operationposition at any time during the transition to the target operationposition is on a transition path in the operational model.
 18. Thevehicle of claim 14, wherein the processor is further configured to:amend an efficiency parameter on a selected position in the operationalmodel according to a calculated efficiency parameter on the targetoperation position.
 19. The vehicle of claim 18, wherein: amending theefficiency parameter on a selected position in the operational modelaccording to the calculated efficiency parameter on the target operationposition comprises: detecting the input voltage and current of the motorat the target operation position; calculating the actual operatingefficiency of the motor at the target operation position according tothe torque and the speed of the motor at the target operation positionand the detected input voltage and current at the target operationposition; calculating a correction coefficient according to theoperating efficiency corresponding to the target operation position inthe operational model and the calculated actual operation efficiency ofthe motor at the target operation position; selecting at least oneposition to be corrected close to the target operation position;calculating the distance between the target operation position and theposition to be corrected; calculating a correction quantity according tothe calculated correction coefficient calculated and the calculateddistance; correcting the position of the position to be corrected in theoperational model according to the correction quantity.